FIG. 3.
Ail is not expressed by Y. pestis strains grown at 6°C. (A) Survival of wild-type and mutant strains of Y. pestis in 80% NHS. Bacteria grown overnight at 6 or 26°C (∼5 × 106 bacteria) were incubated with 80% NHS or HIS for 1 h at 37°C. Aliquots were diluted and plated on TBA plates at 30°C. The percent survival was calculated as follows: average number of bacteria that survived exposure to NHS at 1 h/number of bacteria that survived exposure to HIS at 1 h × 100. (B) Coomassie blue R-250-stained SDS-PAGE gel of whole bacterial cell proteins isolated from wild-type and mutant strains of Y. pestis. The location of the Ail protein is indicated by an arrow. The positions of molecular mass standards (in kilodaltons) are indicated on the left. The strains used were Y. pestis strains KIM8-E (parent), KIM8-E Δy1324 (Δail), and KIM8-E Δy1324 (Δail)/pAil. mw std, molecular mass standards.